Already known in the prior art, there are the flushing or dosing systems involving a hydraulic event used for example in septic fields, or other systems such as irrigation systems. These systems use gravity powers to obtain a fast flow of water. Most often, these prior art flushing systems use a float body which floats up on the surface of the water as the tank fills. The float body is attached to a tank discharge pipe by a flexible coupling which allows the float to lift as the water level rises in the tank, preventing any water from flowing out of the tank. When the water level is high enough, it overflows into the float body, causing the float to loose buoyancy and sink to the bottom of the tank. This action opens a direct path for the water to flow out of the tank. The water in the float empties, allowing the float to regain buoyancy and float up off the bottom of the tank. Examples of such flushing systems are given in U.S. Pat. No. 5,290,434, FR 2,760,030 and FR 2,654,761.
More specifically, U.S. Pat. No. 5,290,434 describes an effluent dosing septic system which comprises a relatively water-tight walled structure capable of accumulating a volume of septic tank effluent; a disposal field dosing system having at least one outlet conduit having an outlet end and an inlet end; a stand pipe which extends from each of the outlet conduits towards the top of the structure; a float having a chamber having an opening on an upper surface thereof; at least one feed conduit having an inlet end located within the chamber and an outlet end in operative connection with the inlet end of the outlet conduit; and a jointed coupler which forms the operative connection between the feed conduit(s) and outlet conduits.
FR 2,760,030 describes a flushing system having a float with a horizontal outlet. The float is attached to an outlet tube. The system is supported by a double, hinged cradle, which rotates around a horizontal axis according to the water level. The position in which water begins to flow is determined by the balance between the thrust produced by the drainage pipe and the attached float and the total weight of the counterweight. The float is attached to a counterweight with one fixed section, which slides over a rod that ensures that the system returns to a height, cutting of the supply to the outlet pipe.
On its side, FR 2,654,761 describes a pendulous drainage device comprising at least one outlet pipe mounted movably between an upper position and a lower position, inside a tank supplied with a liquid, and communicating at its lower part with a discharge conduit situated outside the tank. This device is characterised in that the free end of the outlet pipe comprises a buoyancy unit consisting of an annular cell inside which the mouthpiece of the outlet pipe opens.
Also known in the art, there is FR 2,654,758, which describes a pendulum device for flushing and distributing a liquid. This device comprises at least one drain tube mounted so that it can move between a high position and a low position outside a tank fed by a liquid and communicating at its lower part with the inside of the tank through the use of a siphon. The tube is normally held in a high position inclined with respect to the vertical by means of a ballast. The effect of the ballast is cancelled out under the action of the weight of the liquid filling the tube as the level in the tank gradually rises.
Also known in the prior art, there is FR 2,592,595, which describes a liquid distributor with a hydraulic event involving the gravity energy. The device comprises a source of pressure and a plurality of so-called distribution members downstream of the source of pressure. Each of the distribution members is connected to the source of pressure by at least one discharge tube creating a pressure drop greater than any other pressure drop downstream of the discharge tube.
Among the drawbacks encountered with the above-mentioned documents, there are the followings. These systems do not provide a great flexibility in relation to the water level fluctuation range that is needed for operating the apparatus, and they do not provide a great flexibility for adjusting the mobility of the flushing arm.
Also known in the art, there are systems with siphon. Such systems have the drawback of being easily blocked when operated with wastewater. Furthermore, when these systems are operated with low flow rates, the siphon often does not trigger.
Also known in the art, there are the systems involving the use of pumps. Apart from the fact that these systems require a pump, which is per se a limiting factor, they also have the drawback that pumps consume energy and need maintenance.
Different liquid distribution systems also exist in the prior art for dividing a low flow of wastewater or effluent into equal quantities for distribution to separate discharge pipes in an absorption field. They are the simple T- or Y-shaped flow dividers commercialised under the trademark ZABEL® Z200 and that split the flow of water into two flows. Such divider has the drawback of being easily clogged when operated with wastewater. Another drawback with those flow dividers is that their distribution efficiency relies on an almost perfect levelling of the device, which levelling is almost impossible to maintain in practice because of the movement of the soil caused by its packing and the freezing of the soil.
Also known in the prior art, there are the distribution boxes described in U.S. Pat. No. 6,152,650 or in U.S. Pat. No. 6,112,766. Both these documents disclose a liquid distribution system for distributing effluent from a source of wastewater. The liquid distribution system is contained within a distribution box and includes liquid inlet piping, a ramp system, and a low capacity liquid flow splitting system, including slots and capillary grooves. A high capacity flow splitting system may also be included. In addition, an adjustment system is incorporated into the liquid distribution system for maintaining the level of the liquid distribution system in the ground. As for the above-mentioned flow dividers, one drawback with those distribution boxes is that their distribution efficiency relies on an almost perfect levelling of the box. Another drawback with those distribution boxes is that because there is no regular hydraulic event occurring as in the systems described above which use a float, clogging tends to rapidly occur within the structure. Indeed, the hydraulic event helps preventing the biomass from growing onto the structure.
The flushing apparatus of the present invention is distinct from and overcomes several drawbacks of the prior art devices, as will be discussed in detail below.